Abstract : A Language Oriented Editor (ALOE) is a tool which supports the construction and manipulation of tree structures while guaranteeing their syntactic correctness. Instantiations of ALOEs are generated from a grammatical description of a language. Trees (e.g., programs) are represented internally by ALOEs as abstract syntax trees that the user manipulates directly. A simple language is provided for mapping this internal representation to a concrete representation for display to the user. Complex ALOEs that need more than just syntactic support may provide underlying action routines, extended commands, and environment specific routines. This guide describes how to use and implement an ALOE. (Author)